The need to safely and easily translocate objects without damaging the object or the transfer surfaces, while conserving electric power and manpower resources, spans the gamut of practical applications. Medical, industrial, and shipping environments are but a few examples in which it is often extremely difficult to easily and practically move an object over a surface, even with the aid of some sort of transfer device assisting in the transport.
The range of applications desiring an improved transport device is vast. Examples of objects which require occasional, careful and economically feasible transport include artistic sculptures or other museum exhibits, and animals in need of medical attention at farms, zoos, conservation sites or veterinary hospitals. Moving objects in the shipping industry is yet another application desiring a transfer mechanism using less manpower resources and decreased electric power consumption requirements. Such an economically efficient transfer mechanism would provide great benefits to those in industry who are charged with the often complex and burdensome tasks associated with transferring loads from one locale to another such as, for example, shipping vessels (e.g., air, truck, rail, and cargo ship freight) to storage facilities (e.g., warehouses, docks, and the like).
It is often necessary to move persons, such as accident victims, the elderly, comatose, paralyzed or otherwise immobilized patients, from one support surface, such as a bed, to another support surface, such as a gurney or wheeled hospital cart. There are many difficulties confronting those responsible for moving such immobilized or fragile persons in a safe, comfortable manner, while, at the same time, attempting to conserve manpower and electrical energy resources. For example, patients who cannot sit up or move by themselves can be particularly difficult to move from a stretcher to a bed or vice versa, and the only way to safely reposition such fragile patients is to use two or three nurses, orderlies or other attendants.
Prior art patient transfer devices frequently take the form of “floating” or air-elevated air mattress-type movers. Examples of such air mattress-type movers are disclosed in U.S. Pat. No. 6,073,291 to David T. Davis and U.S. Pat. No. 5,561,873 to Robert E. Weedling, the entireties of which are incorporated herein by reference. These prior art mattress-type transfer devices include small perforations in the bottom and are inflated with air to obtain and at least temporarily maintain the mattress in an inflated state. During such inflation, a continuous supply of pressurized air is expelled from the bottom of the transfer device through the perforations to form an air film which supports the inflated transfer device on any reasonably flat, semi-continuous surface, in the same manner as an air pallet used for industrial applications within shops, plants and warehouses.
The prior art inflatable transfer devices operate by continuously supplying air under pressure into a plenum chamber, which is defined by the transfer structure itself, in a sufficient amount to maintain inflation of the plenum chamber. These prior art inflatable transfer devices have a serious drawback, however, in that only a relatively weak air film is provided due to the free and unchecked dissipation of air from the fluid film beneath the transfer device. The poor quality air film can be attributed to the fact that the prior art devices fail to provide a structure that controls the distribution of air that continuously exits the perforations in the bottom of the transfer apparatus. One particularly disfavorable effect of not controlling the dissipation of air is that greater pulling efforts are required to move the transfer device over a transporting surface. This problem is exacerbated by sudden degassing when the transfer device encounters even small gaps or breaks in an irregular transporting surface. This problem also presents a serious risk of injury for those who pull such a transport device, especially if insufficient manpower is available to meet the increased pulling demands resulting from the weak air film underneath the transfer device. In addition to the above, the transfer device itself is susceptible to abrasion damage from the increased frictional forces exerted on the bottom of the transfer device as a result of the weak air film. In that manner, the lack of a suitable air film underneath the device not only creates substantial risks of injury to personnel but also tends to shorten the life and inhibit the function of the transfer device itself.
Another serious drawback related to the unchecked dissipation of air from underneath prior art transfer devices is that more electric power is needed to continuously resupply the dissipating air film. Accordingly, the air blowers used to inflate prior art transfer structures tend to consume relatively large amounts of electric power during use. In the context of transporting a medical patient, the patient is thus continuously exposed to the typically loud and often unsettling sounds associated with using such high power blower units during transport.
As mentioned above, the poor quality of the air films associated with the prior art transfer devices is attributed, at least in part, to the fact that the prior art devices do not inhibit or even control the random dissipation of air from the air film underneath the bottom portion thereof. For example, even though FIG. 2 of the '291 patent appears to show that the central portion of the bottom sheet is raised or elevated with respect to the outer peripheral portions, this drawing is merely an artist's rendition of the prior art air mattress in a free-standing state (i.e., not in use to create a fluid film for transport). This rendition is misleading, however, because it is clear that the central portion of the '291 bottom sheet is not raised or elevated with respect to the outer peripheral portions when the transfer apparatus is actually used on a transfer surface. This is clear from the other views of the air mattress shown in FIGS. 5-7 of the '291 patent and the explicit disclosure of the '291 patent itself, which recites that when the transfer apparatus is resting on a more or less level surface as in actual use, the bottom also assumes a more or less planar configuration and the raised sides and portions of the top surface become even more pronounced. Without providing any structures that actually function to contain or control the rate of air dispersion from the air film underneath the essentially flat bottom surface of the air mattress, a prior art air mattress such as that of the '291 patent suffers from the same drawbacks relating to poor quality air films discussed above. In addition, the operating costs associated with the prior art transfer apparatus shown in the '291 patent are undesirably high due to the high demand for electric power required to operate an air blower to maintain sufficient plenum chamber inflation and required to counter-balance the high, steady and otherwise uncontrolled rate of air dissipation from the fluid film beneath the transfer apparatus.
Prior art inflatable transfer apparatuses are further plagued by plenum chamber air loss due to the ill effects of certain types of stresses that are placed on stitched seam lines connecting various sheets making up the transfer devices. These types of stresses originate from the internal pressure required to maintain the inflated state of the plenum chamber and the vertical and/or lateral external mechanical stresses that are placed upon the transfer devices during load transfer. FIG. 9 of the present application illustrates such a prior art seam line structure, including portions of top sheet 100 and bottom sheet 200 that are folded under to form a double layer of top and bottom sheets 100 and 200, respectively, and the double layers are placed parallel to one another and stitched to form the seam line junction. Due to the stretching motion imposed on the sheets during high pressure inflation and due to the vertical and/or lateral stresses imposed on the seam lines during operation, separations or gaps tend to develop between top sheet 100 and bottom sheet 200 during use of the transfer apparatus. Air loss from the plenum chamber through such seam line separations or gaps further reduces the efficiency of the transfer apparatus by causing the need to supply an even higher level of electric power to the blower unit in order to maintain an inflated plenum chamber and the desired fluid film therebeneath. Prior art transfer devices that are susceptible to such air loss through such seam lines, coupled with a lack of fluid film retention means beneath the air mattress, are dangerous to use, suffer from a reduced useful life, and require a high power blower that is typically more costly, bulky and which disadvantageously consumes a large amount of electricity.
Yet another problem associated with prior art air mattress-type movers is that the air inlet for receiving a hose or connection conduit from the blower unit is typically positioned in only a single location on the air mattress, most often at the head-end. Although some prior art transfer devices offer air inlets on both sides at the head-end in an effort to improve access, it is still often inconvenient to connect a blower hose to the air mattress at this location, particularly when a patient's head is positioned in close proximity thereto. Further, since the blower hose or connection conduit typically extends perpendicularly from the air mattress, a substantial amount of clearance must be provided at that portion of the air mattress to facilitate this connection. In a health care setting, this means that the specific location of the air inlet not only dictates where a patient can be comfortably positioned thereon, but also dictates where the air mattress can be located for use within a given room, hallway or the like.
A further problem associated with prior art transfer devices is that the blower hose is usually inserted into an air inlet in the mattresses without providing any particular means for retaining the hose in the air mattress during operation. As such, in the event of a sudden load shift, or if a patient is obese, for example, the possibility that the blower hose will be forced back out of the air inlet due to the increased air pressure within the air mattress plenum chamber presents a dangerous situation. If the blower is operating at a high power, such as that typically required of air blowers for the prior art transfer devices for the reasons mentioned above, the suddenly disconnected blower hose could flail about and potentially cause a significant threat of injury to the patient or the medical personnel operating the air mattress. This would also cause sudden degassing of the plenum chamber by cutting off the pressurized fluid supply. Conversely, a sudden degassing of the plenum chamber could also dislodge the air hose and further harm a patient on the transfer device, or another type of load positioned on the transfer apparatus, or nearby personnel.
In view of the foregoing, it would be desirable to provide a material mover employing a structure for defining, maintaining, and controlling the fluid dissipation of a fluid film reservoir beneath a bottom portion of an inflatable transfer device, as well as to provide an improved fluid-retaining seam line junction between the sheet material defining the transfer device itself. It would also be desirable to provide air inlets in a plurality of positions to beneficially allow the blower hose to be connected to the air mattress at multiple locations along the air mattress, which increases the number of possible locations within a room, a hallway, or the like, where the air mattress could be used, and thus, increases the practical applicability of such transfer devices in crowded storage container or warehouse situations as well as in the health care setting. Further, it would be desirable to provide a reliable and secure connection between the transfer device and the blower hose of the inflation device (fluid provider or blower) that improves both the safety and convenience associated with the use of the transfer device.